#define _CRT_SECURE_NO_WARNINGS 1
int missingNumber(int* nums, int numsSize)
{
    int n = numsSize + 1;
    int count = 0;
    for (int i = 0; i < numsSize; i++)
    {
        count += nums[i];
    }
    int Sn = (n * (n - 1)) / 2;
    return Sn - count;
}
